[ML-5] Ohtahara syndrome: The connection between brain development and epileptic encephalopathy
In 1976, Professor Ohtahara identified a characteristic group of infants, mainly neonates, with tonic spasms and suppression-burst pattern on EEG that was distinct from periodic hypsarrhythmia or burst-suppression patterns in neonatal hypoxic-ischemic encephalopathy. He named this as early-infantile epileptic encephalopathy with suppression-burst that was later renamed Ohtahara syndrome (OS) and included in the ILAE international classification of epilepsy and epileptic syndromes. Follow-up studies revealed frequent evolution from OS to West syndrome (WS) and from WS to Lennox-Gastaut syndrome. These three syndromes share the following common characteristics: (1) occurrence in a specific age range, (2) frequent and intractable generalized minor seizures of particular types, (3) massive and continuous epileptic EEG abnormalities, (4) etiological heterogeneity, and (5) unfavorable prognosis for psychomotor development. These syndromes may be an age-specific epileptic reaction of the brain at certain developmental stages to various nonspecific exogenous brain insults and/or endogenous/genetically determined brain dysfunction. The evolution and common characteristics among these three epileptic syndromes led him to the idea that these syndromes belong to a group of age-dependent epileptic encephalopathies. More than a half century ago, Professor Ohtahara started his research by focusing on two main issues, brain development and childhood refractory epilepsies. He shed light on occurrence of severe childhood epilepsies according to the developmental process by delineating the concept of age-dependent epileptic encephalopathy. The discovery of OS and the concept of age-dependent epileptic encephalopathy were truly novel and led to an understanding of the significance of brain development in the occurrence of childhood